// In the name of the God
#include <bits/stdc++.h>
#define ll long long
#define int long long
#define pb push_back
#define F first
#define S second
#define mp make_pair
#define pii pair <int, int>
#define smin(x, y) (x) = min((x), (y))
#define smax(x, y) (x) = max((x), (y))
#define all(x) (x).begin(), (x).end()
using namespace std;
// #pragma GCC optimize("O3,unroll-loops")
// #pragma GCC target("avx2")
const int inf = (1e9+7)*(1e9+7);
const int mod = 998244353;
const int maxn = 1e2+5, maxk = 1e3+5;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
int n, m, k, d1[maxn][maxn], d2[maxn][maxn], b[maxn][maxk], s[maxn][maxk], p[maxn][maxn];
void fw(int d[maxn][maxn]) {
for (int i = 0; i < n; i++)
for (int j = 0; j < n; j++)
for (int l = 0; l < n; l++) smin(d[j][l], d[j][i]+d[i][l]);
}
int32_t main() {
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> n >> m >> k;
for (int i = 0; i < n; i++) {
for (int j = 0; j < k; j++) cin >> b[i][j] >> s[i][j];
for (int j = 0; j < n; j++) d1[i][j] = inf;
}
for (int i = 0; i < m; i++) {
int v, u, w; cin >> v >> u >> w;
d1[--v][--u] = w;
}
fw(d1);
for (int i = 0; i < n; i++)
for (int j = 0; j < n; j++)
for (int l = 0; l < k; l++)
if (b[i][l] != -1 and s[j][l] != -1) smax(p[i][j], s[j][l]-b[i][l]);
int l = 0, r = 1e9+10;
while (r-l > 1) {
int mid = (l+r)/2;
for (int i = 0; i < n; i++)
for (int j = 0; j < n; j++) d2[i][j] = mid*min(d1[i][j], inf/mid)-p[i][j];
fw(d2);
bool nc = 0;
for (int i = 0; i < n; i++)
if (d2[i][i] <= 0) nc = 1;
if (nc) l = mid;
else r = mid;
}
cout << l << '\n';
return 0;
}
/*
srand(time(0));
cout << (rand()%1900) + 1 << ' ' << (rand()%2)+5 << '\n';
*/
